There are two Cores. Core A is the administrative core, which provides administrative support for scheduling subjects and handles purchasing, accounting, and general administrative functions for all projects. Core B is the Human Subjects Core where the primary functions are the recruitment of human subjects from majority and minority populations for participation in the longitudinal study of age-related hearing loss and in experiments proposed in Projects 1-3; collection, storage, and analysis of demographic, audiologic, and biologic/medical data and tissue (blood and DMA) from subjects enrolling in the longitudinal study, which covers the past 20 years and the next five years; and coordination of subject schedules for the audiologic and medical test battery, annual evaluations, and longitudinal measures.